Practice Essentials

Pica is an eating disorder typically defined as the persistent ingestion of nonnutritive substances for at least 1 month at an age for which this behavior is developmentally inappropriate. It may be benign or may have life-threatening consequences.

Signs and symptoms

The clinical presentation of pica is highly variable and is associated with the specific nature of the resulting medical conditions and the ingested substances. In poisoning or exposure to infectious agents, the reported symptoms are extremely variable and are related to the type of toxin or infectious agent ingested.

Physical findings may include the following:

Manifestations of toxic ingestion (eg, lead poisoning)

Manifestations of infection or parasitic infestation (eg, toxocariasis and ascariasis)

Diagnosis

No specific laboratory studies are indicated in the evaluation of pica. However, certain laboratory studies may be indicated to assess the consequences of the condition. Screening of blood lead concentrations is recommended for the following:

All children aged 1-2 years in localities where at least 27% of houses were built before 1950

All places where the prevalence of elevated blood levels in children aged 1-2 years is 12% or higher

High-risk 1- and 2-year-old children

Imaging studies used to identify ingested materials and aid in the management of gastrointestinal (GI) tract complications of pica may include the following:

Management

A multidisciplinary approach involving psychologists, social workers, and physicians is recommended for effective treatment.

No medical treatment is specific for pica. Some evidence suggests that drugs that enhance dopaminergic functioning (eg, olanzapine) may provide treatment alternatives in individuals with pica that is refractory to behavioral intervention.

Currently, behavioral strategies are considered the most effective in the treatment of pica. Such strategies include the following:

Antecedent manipulation

Training in discrimination between edible and nonedible items

Self-protection devices that prohibit placement of objects in the mouth

Background

Pica is typically defined as persistent ingestion of nonnutritive substances for at least 1 month at an age for which this behavior is developmentally inappropriate.
[1] The definition is occasionally broadened to include the mouthing of nonnutritive substances. Pica may be benign, or it may have life-threatening consequences.

Although pica is observed most frequently in children, it is the most common eating disorder in individuals with developmental disabilities. It has also been observed in females during pregnancy. In some societies, pica is a culturally sanctioned practice and is not considered pathologic.

Although pica can impair physical functioning, it rarely causes impairment of social functioning, which is typically associated with comorbid disorders. The most common of these disorders are autism spectrum disorder, intellectual disability, and, to a lesser degree, schizophrenia and obsessive-compulsive disorder (OCD). When pica coexists with trichotillomania or excoriation, the hair or skin is typically ingested. Pica may also coexist with avoidant/restrictive food intake disorder, especially when there is a strong sensory component to the presentation.

Diagnostic criteria (DSM-5)

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), classifies pica under feeding and eating disorders and notes that it may be present in conjunction with other feeding and eating disorders.
[1] DSM-5 criteria for pica are as follows:

Persistent eating of nonnutritive, nonfood substances over a period of at least 1 month

The eating of such substances is inappropriate to the developmental level of the individual

The eating behavior is not part of a culturally supported or socially normative practice

If the behavior occurs within the context of another mental disorder or medical condition (eg, schizophrenia, autism, or pregnancy), it is sufficiently severe to warrant independent clinical attention

A minimum age of 2 years is suggested for the diagnosis. In children aged 18 months to 2 years, the ingestion and mouthing of nonnutritive substances is common and is not considered pathologic.

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Etiology

Although the etiology of pica is unknown, numerous hypotheses have been advanced to explain the phenomenon, ranging from psychosocial causes to causes of purely biochemical origin. Suggested causes include the following:

Nutritional deficiencies

Cultural and familial factors

Stress

Low socioeconomic status

Nondiscriminating oral behavior

Learned behavior

Underlying biochemical disorder

Although no firm empiric data support any of the nutritional etiologic hypotheses, deficiencies in iron, calcium, zinc, and other nutrients (eg, thiamine, niacin, and vitamins C and D) have been associated with pica. In some patients with malnutrition who eat clay, iron deficiencies have been diagnosed, but the direction of this causal association is unclear. Whether the iron deficiency prompted the eating of clay or whether the inhibition of iron absorption caused by the ingestion of clay produced the iron deficiency is unknown.

Current methodologies for the physical, mineralogic, and chemical characterization of pica substances, particularly clay and soil, may be useful for determining the bioavailability of nutrients and other bioactive components and for generating data to support or negate these nutritional hypotheses.
[2]

Ingestion of clay, soil, or starch may be regarded as culturally acceptable by certain social groups. Clay eating and starch eating are seen in the United States in some southern, rural, African American communities, primarily among women and children. Starch eating, in particular, is frequently started in pregnancy as a treatment for morning sickness and may be continued into the postpartum period. Parents may proactively teach their children to eat these and other substances. Pica behavior may also be learned via modeling and reinforcement.

Ingestion of paint is most common in children from families of low socioeconomic status and is associated with lack of parental supervision. Malnutrition and hunger may also result in pica.

It has been suggested that in individuals with intellectual disability, pica may result from an inability to discriminate between food and nonfood items; however, the findings that individuals select pica items and that they often search aggressively search for nonfood items of choice do not support this theory.

In individuals with intellectual and developmental disabilities in particular, the traditional view is that the occurrence of pica is a learned behavior maintained by the consequences of that behavior.

The association of pica, iron deficiency, and a number of pathophysiologic states with decreased activity of the dopamine system suggests the possibility of a correlation between diminished dopaminergic neurotransmission and the expression and maintenance of pica.
[3] To date, however, no specific pathogenesis resulting from any underlying biochemical disorders has been identified empirically.

Risk factors for pica include the following:

Parent-child psychopathology

Family disorganization

Environmental deprivation

Pregnancy

Epilepsy

Brain damage

Intellectual disability

Developmental disorders

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Epidemiology

United States statistics

Because pica is often unrecognized and underreported, its true prevalence is unknown. Although prevalence rates vary depending on the definition of pica employed, the characteristics of the population sampled, and the methods used for data collection, pica is reported most commonly in children and in individuals with intellectual disability.

Children with intellectual disability and autism are affected more frequently than children without these conditions. Among individuals with intellectual disability, pica is the most common eating disorder. In this population, the risk for and severity of pica increase as the severity of the disability increases.

International statistics

Pica occurs throughout the world. Geophagia (deliberate consumption of earth, soil or clay) is the most common form of pica in people who live in poverty and people who live in the tropics and in tribe-oriented societies. Pica is a widespread practice in western Kenya, southern Africa, and India. It has been reported in Australia, Canada, Israel, Iran, Uganda, Wales, Turkey, and Jamaica. In some countries (eg, Uganda) soil can be purchased for the purpose of ingestion.

Age-, sex-, and race-related demographics

Pica is observed more commonly during the second and third years of life and is considered developmentally inappropriate in children older than 18-24 months. Research suggests that pica occurs in 25-33% of young children and 20% of children seen in mental health clinics. A linear decrease in pica occurs with increasing age. Pica occasionally extends into adolescence but is rarely observed in adults who are not mentally disabled. Among individuals with intellectual disability, pica occurs most often in those aged 10-20 years.
[4]

In young pregnant women, the onset of pica frequently occurs during their first pregnancy in late adolescence or early adulthood. Although the pica usually remits at the end of the pregnancy, it may continue intermittently for years.
[5] Worldwide prevalence of pica during pregnancy and the postpartum period has been estimated at 27.8%.
[6]

Pica typically occurs with equal frequency in boys and girls; however, it is rare in adolescent and adult males of average intelligence who live in developed countries.

Although no specific data exist regarding the racial predilection of pica, the practice is reported to be more common among certain cultural and geographic populations. For example, geophagia is accepted culturally among some families of African lineage and is reported to be problematic in 70% of the provinces in Turkey.

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Prognosis

Pica often remits spontaneously in young children and pregnant women; however, it may persist for years if untreated, especially in individuals with intellectual and developmental disabilities.

Pica is a serious behavioral problem because it can result in significant medical sequelae, which are determined by the nature and amount of the ingested substance. Pica has been shown to be a predisposing factor in accidental ingestion of poisons, particularly in lead poisoning. The ingestion of bizarre or unusual substances has also resulted in other potentially life-threatening toxicities, such as hyperkalemia after cautopyreiophagia (ingestion of burnt match heads).

Exposure to infectious agents via ingestion of contaminated substances is another potential health hazard associated with pica, the nature of which varies with the content of the ingested material. In particular, geophagia (soil or clay ingestion) has been associated with soil-borne parasitic infections (eg, toxoplasmosis and toxocariasis). Gastrointestinal (GI) tract complications (eg, mechanical bowel problems, constipation, ulcerations, perforations, and intestinal obstructions) have resulted from pica.

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Patient Education

It is vital to educate patients regarding healthy nutritional practices. Failure to inform patients of the dangers of eating nonnutritive substances is a management pitfall to be avoided.

In some areas, homeowners and landlords are legally responsible for lead hazard reduction in homes where hazardous lead-based paint conditions have been discovered either after direct testing or after a child inhabitant is found to have elevated blood lead levels. Remediation of the residence by licensed lead abatement professionals will eliminate lead hazards by removing, sealing, or enclosing lead-based paint with special materials. Temporary relocation of the child may be required.

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Clinical Presentation

History

The clinical presentation of pica is highly variable and is associated with the specific nature of the resulting medical conditions and the ingested substances. In poisoning or exposure to infectious agents, the reported symptoms are extremely variable and are related to the type of toxin or infectious agent ingested. Gastrointestinal (GI) tract symptoms may include constipation, chronic or acute abdominal pain that may be diffuse or focused, nausea and vomiting, abdominal distention, and loss of appetite.

Patients may withhold information regarding pica behavior and deny the presence of pica when questioned. This secretiveness frequently interferes with accurate diagnosis and effective treatment. The broad range of complications arising from the various forms of pica and the delay in accurate diagnosis may result in mild–to–life-threatening sequelae.

Physical Examination

The physical findings associated with pica are extremely variable and are related directly to the materials ingested and the subsequent medical consequences. These findings may include the following:

Manifestations of toxic ingestion (eg, lead poisoning)

Manifestations of infection or parasitic infestation

GI manifestations

Dental manifestations

Physical manifestations associated with lead poisoning (the most common poisoning associated with pica) are nonspecific and subtle, and most children with lead poisoning are asymptomatic. These manifestations can include neurologic symptoms (eg, irritability, lethargy, ataxia, incoordination, headache, cranial nerve paralysis, papilledema, encephalopathy, seizures, coma, or death) and GI tract symptoms (eg, constipation, abdominal pain, colic, vomiting, anorexia, or diarrhea).

Toxocariasis (including visceral larva migrans and ocular larva migrans) and ascariasis are the most common soil-borne parasitic infections associated with pica. Manifestations of toxocariasis are diverse and appear to be related to the number of larvae ingested and the organs to which the larvae migrate. Physical findings associated with visceral larva migrans may include fever, hepatomegaly, malaise, coughing, myocarditis, and encephalitis. Ocular larva migrans can result in retinal lesions and loss of vision.

GI tract manifestations may be evident secondary to mechanical bowel problems, constipation, ulcerations, perforations, and intestinal obstructions caused by bezoar formation and the ingestion of indigestible materials into the GI tract.

Complications

Lead toxicity has neurologic, hematologic, endocrine, cardiovascular, and renal effects. Lead encephalopathy is a potentially fatal complication of severe lead poisoning, presenting with headache, vomiting, seizures, coma, and respiratory arrest.

Ingestion of high doses of lead can cause significant intellectual impairment and behavioral and learning problems. It has been demonstrated that neuropsychologic dysfunction and deficits in neurologic development can result from very low lead levels, even levels once considered safe. A hypochromic microcytic anemia resembling iron deficiency anemia can also be seen with lead toxicity; lead interferes with heme synthesis, beginning at blood lead concentrations of about 25 µg/dL.

Various infections and parasitic infestations, ranging from mild to severe, are associated with the ingestion of infectious agents via contaminated substances, such as feces or dirt. In particular, geophagia has been associated with soil-borne parasitic infections, such as toxocariasis, toxoplasmosis, and trichuriasis.

Nutritional effects may also be evident. Theories regarding the direct nutritional effects of pica are related to characteristics of specific ingested materials that either displace normal dietary intake or interfere with the absorption of necessary nutritional substances. Nutritional effects that have been linked to severe cases of pica include iron and zinc deficiency syndromes; however, the data are only suggestive, and there is no firm empiric evidence to support these theories.
[9]

A meta-analysis of 43 studies including 6,407 individuals with pica behaviors and 10,277 controls found pica to be associated with 2.35 greater odds of anemia and low hemoglobin (Hb), hematocrit (Hct), or plasma zinc (Zn) concentrations.
[10]

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Differential Diagnosis

Diagnostic Considerations

Ingestion of nonnutritive, nonfood substances may also be observed in individuals with autism, schizophrenia, or certain physical disorders (eg, Kleine-Levin syndrome). In such instances, pica should be noted as an additional diagnosis only if the eating behavior is severe enough to warrant additional clinical attention.

Differentials

Workup

Laboratory Studies

No specific laboratory studies are indicated in the evaluation of pica. However, certain laboratory studies may be indicated to assess the consequences of the condition, depending on the characteristics and nature of the ingested materials and the resultant medical sequelae.

Universal screening of blood lead concentrations in all children aged 1-2 years is recommended in localities where at least 27% of houses were built before 1950. Screening is also recommended in places where the prevalence of elevated blood levels in children aged 1-2 years is 12% or higher. Targeted screening for high-risk 1- and 2-year-old children is otherwise recommended.

Radiography and Endoscopy

Various imaging studies may be used to identify ingested materials and aid in the management of gastrointestinal (GI) tract complications of pica. These may include the following:

Abdominal radiography

Upper and lower GI barium examinations

Repeated imaging at regular intervals to track changes in location of ingested materials

Treatment & Management

Approach Considerations

Although pica in children often remits spontaneously, a multidisciplinary approach involving psychologists, social workers, and physicians is recommended for effective treatment.
[11] Development of the treatment plan must take into account the symptoms of pica and any contributing factors, as well as the management of possible complications of the disorder. Treatment of pica is conducted primarily on an outpatient basis.

Assessment of nutritional beliefs may be relevant in the treatment of some patients with pica. Any nutritional deficiencies that are identified should be addressed. It must be kept in mind, however, that nutritional and dietary approaches have successfully helped prevent pica in only a very limited number of patients.

Consultation with a psychologist or psychiatrist is advisable. Consultation with a social worker is also helpful.

A dentist may be consulted as well. Attention to oral health is important for managing the detrimental effects pica may have on teeth from a young age onward.
[12]

Pharmacologic Therapy

No medical treatment is specific for pica. Few studies of pharmacologic therapy for pica have been performed; however, the hypothesis that diminished dopaminergic neurotransmission is associated with pica suggests that drugs that enhance dopaminergic functioning may provide treatment alternatives in individuals with pica that is refractory to behavioral intervention.
[3]

In addition, a single case report found that olanzapine, an antipsychotic agent with prominent dopaminergic, serotoninergic, adrenergic, and cholinergic effects, reduced pica behaviors.
[13] Medications used in the management of severe behavioral problems may have a positive impact on comorbid pica.

Psychosocial Interventions

Careful analysis of the function of pica behavior in individual patients is critical for effective treatment. Currently, behavioral strategies are considered the most effective in the treatment of pica. Such strategies include the following:

Antecedent manipulation

Training in discrimination between edible and nonedible items

Self-protection devices that prohibit placement of objects in the mouth

In toddlers and young children, pica behavior may provide environmental or sensory stimulation. Assistance in addressing these issues may prove beneficial, along with help in managing economic problems or alleviating deprivation and social isolation. Assessment of cultural beliefs and traditions may reveal the need for education regarding the negative effects of pica. Removal of toxic substances—especially lead-based paint—from the environment is important.